Living in a dangerous world decreases maternal care: A study in serotonin transporter knockout mice

► We confronted pregnant and lactating mice with unfamiliar male-soiled bedding (UMB). ► These stimuli signal the danger of infant killing and indicate a “dangerous world”. ► After the first treatment with UMB mothers showed an increased stress response. ► Furthermore, living in a “dangerous world” distinctly reduced maternal care behavior. ► Maternal care may mediate the effects of early adversity on offspring behavior.